Gold ball having a foamed layer created by infrared radiation

ABSTRACT

This invention is directed to a golf ball having a foamed layer and the method for creating the foamed layer by the heating of blowing agents with infrared radiation. Either physical blowing agents can be de-volatized, or chemical blowing agents (both organic and inorganic) may be decomposed wherein the blowing agents are generated within the layer. The resultant layer is less dense than the core layer beneath it.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of co-pending U.S. application Ser. No. 10/341,572, which was a divisional of co-pending U.S. application Ser. No. 10/141,481 which was filed May 8, 2002, and now is U.S. Pat. No. 6,855,070, and is incorporated herein in its entirety by express reference thereto.

FIELD OF THE INVENTION

This invention relates to the utilization of infrared radiation to form a foamed layer, cross-linking an intermediate layer, and post-curing a cover layer.

BACKGROUND OF THE INVENTION

Generally, golf balls have been classified as wound balls or solid balls. Wound balls are generally constructed from a liquid or solid center surrounded by tensioned elastomeric material. Wound balls are generally thought of as performance golf balls and have a good resiliency, spin characteristics and feel when struck by a golf club. However, wound balls are generally difficult to manufacture when compared to solid golf balls.

Solid golf balls were initially, two piece balls, i.e., comprising a core and a cover. More recently developed solid balls are comprised of a core, one or more mantle layers and one or more covers, in order to improve the playing characteristics of the ball.

In the manufacture of solid golf ball cores, all cores have a slight cure gradient. This is a normal result of the cure conditions, which usually heat from the outside in. The current practice is generally to form a core with the most uniformity for the given construction. If it is desired to create cure gradients having large differences, or to use materials that are not typical to the art, generally, it has been necessary to use high molding temperatures for long periods of time (i.e. 175° C. for 30 minutes).

The prior art is comprised of a variety of golf balls that have been designed to provide particular playing characteristics. These characteristics are generally the initial velocity and spin of the golf ball, which can be optimized for various types of players. For instance, certain players prefer a ball that has a high spin rate in order to control and stop the golf ball. Other players prefer a ball that has a low spin rate and high resiliency to maximize distance. Generally, a golf ball having a hard core and a soft cover will have a high spin rate. Conversely, a golf ball having a hard cover and a soft core will have a low spin rate. Golf balls having a hard core and a hard cover generally have very high resiliency for distance, but are hard feeling and difficult to control around the greens. Various prior art references have been directed to adding a mantle layer or second cover layer to improve the playability of solid golf balls.

As indicated above, the spin rate of golf balls is the end result of many variables, softness of the cover in relationship to the inner core or an inner mantle layer is but one of these variables. Spin rate is an important characteristic of golf balls for both skilled and recreational golfers. High spin rate allows the more skilled players, such as PGA professionals and low handicapped players, to maximize control of the golf ball. A high spin rate golf ball is advantageous for an approach shot to the green. The ability to produce and control backspin to stop the ball on the green and side spin to draw or fade the ball substantially improves the player's control over the ball. Hence, the more skilled players generally prefer a golf ball that exhibits high spin rate.

On the other hand, recreational players who cannot intentionally control the spin of the ball generally do not prefer a high spin rate golf ball. For these players, slicing and hooking are the more immediate obstacles. When a club head strikes a ball, an unintentional side spin is often imparted to the ball, which sends the ball off its intended course. The side spin reduces the player's control over the ball, as well as the distance the ball will travel. A golf ball that spins less tends not to drift off-line erratically if the shot is not hit squarely off the club face. The low spin ball will not cure the hook or the slice, but the lower spin will reduce the adverse effects of the side spin. Hence, recreational players prefer a golf ball that exhibits low spin rate.

The prior art teaches of having either a soft or a hard intermediate (inner cover) layer formed about a core to achieve particular performances, as seen above, from a golf ball. A means of achieving these types of performance characteristics without the use of any mantle layer may be attainable through the use of gradient curing to create hardness gradients on the outer skin or shell of the golf ball core.

U.S. Pat. Nos. 5,803,834, 5,733,206, 5,976,443, 6,113,831, 5,697,856, 4,650,193, 4,570,937, and 4,858,924 are examples of creating gradients in the core of a golf ball.

SUMMARY OF THE INVENTION

The invention provides a method for forming in a multilayer golf ball, an intermediate layer comprising an expandable polymeric composition containing a blowing agent, wherein the expandable polymeric composition expands from 5% to 200% of its pre-expand thickness when the expandable polymeric composition is heated with infrared radiation at a specific temperature and predetermined time. The intermediate layer has a density less than the core.

In one embodiment, the blowing agent is a thermally decomposable inorganic chemical blowing agent selected from the group consisting of ammonium carbonate and carbonates of alkali metals.

In yet another embodiment, the blowing agent is a thermally decomposable organic blowing agent selected from the group consisting of azo and diazo compounds, nitroso compounds, sulfonylhydrazides, azides of organic acids and their analogs, triazines, tri-and tetrazole derivatives, sulfonyl semicarbazides, urea derivatives, guanidine derivatives, or esters such as alkoxyboroxines.

One embodiment discloses a blowing agent that is a de-volatizable physical blowing agent selected from a volatile liquid group consisting of freons, halogenated hydrocarbons, water, aliphatic hydrocarbons, gases, or solid adsorbents that liberate gas as a result of desorption of gas. The solid adsorbents are selected from a group consisting of activated carbon, calcium carbonate, diatomaceous earth, and silicates saturated with carbon dioxide.

An embodiment of the invention provides the expandable polymeric composition to be comprised of a plurality of thermally expandable polyspheres encapsulating an expandable blowing agent in the form of a solvent, wherein when heated by infrared radiation the solvent expands into a gas that is released into the layer.

The blowing agent of the present invention may liberate a gas as a result of a chemical interaction between components selected from a group consisting of mixtures of acids and metals, mixtures of organic acids and inorganic carbonates, mixtures of nitrites and ammonium salts and the hydrolytic decomposition of urea.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The method of the present invention includes creating gradients upon a spherical object such as golf ball core and a cover. The method of the invention would work equally as well with one-piece balls as described in U.S. Pat. No. 6,162,135, multi-layer core balls or a ball made with a laminated construction as described in U.S. Pat. No. 6,056,842, which is incorporated by reference herein in its entirety.

As previously stated, in the manufacture of golf balls, all golf balls have a slight cure gradient that is created by the very nature of the cure conditions, which is heating from the outside in. The cure conditions are optimized to create the cure with the most uniformity for the given construction. If cure gradients that have large differences were desired or if materials that are not typical of the art were desired, then they could be achieved with high molding temperatures for long periods of time (i.e. 175° C. for 30 minutes).

The present invention employs the method of Infrared Radiation (IR) for forming a foamed layer in intermediate and cover layers. The description herein will focus mainly upon the forming of foamed layers, however, it is to be appreciated that IR represents a potential alternative means of cross-linking any portion of a ball, including a cover, a coating or any intermediate layer.

The Electromagnetic Spectrum includes all types of radiation: Gamma-rays, X-rays, Ultraviolets, visible light, infrared light, microwaves and radio waves. All these rays and waves in the Electromagnetic Spectrum are different only because the length of their waves are different. Short wavelength radiation is of the highest energy and can be very dangerous (X-rays and Ultraviolets). Longer wavelength radiation, which includes IR, is of lower energy and usually is harmless. IR radiation is a very radiant form of heating. It heats objects and people directly, without the need to heat up the air in between. The prefix “infra” is Latin for below and refers to the wavelengths that are below the red end of the visible spectrum. IR radiation is generally split into three wavelengths: short-wave, medium-wave and long-wave. The wavelengths can vary from 0.7 microns to about 100 microns. For each of these types of infra-red heating, there is a wide choice of emitter and wavelength. Selection of the correct type for a particular application is usually critical. The type of wavelength employed in the present invention is the medium-length wherein the emitter operates at bright red heat. The absorption wavelengths of C═C groups which include butadiene is about 6.07 microns. The absorption range for most of the materials reported in this invention fall between about 5 to 6.8 microns. The type of emitter to provide IR in this range are well known by those in the field and medium-wave panels can be easily retrofitted to existing hot air or contra-flow ovens. The following U.S. Pat. Nos. 6,174,388, 6,024,813, 5,677,362, 5,672,393, and 5,665,192, which are incorporated by reference herein in their entirety, describe various methods of curing with IR (although not of a golf ball core or cover).

Disclosed herein is a novel methodology in the use of rubbers, curing agents and high temperature peroxides in normal formulations, in such a way that they will not fully cure when molded, but will more fully cure when exposed to infrared radiation. Preferably, they will then be more fully cured only at the first several mils on the surface of the golf ball core/air interface. This results in a highly cross-linked surface and a soft center. This may be completed in a short time span, i.e. 5 minutes if by infrared radiation. The core having been molded, the structural framework will stay intact. The outside core surface will experience high (175-300° C.) temperatures.

The following terms are used in this application. Shore D and C Harnesses are measured by the ASTM method D-2240. “Compression points” refer to the compression scale or the compression scale based on the ATTI Engineering Compression Tester. This scale, which is well known to those working in this field, is used in determining the relative compression of a core or ball. The compression is measured by applying a spring-loaded force to the golf ball center, golf ball core or the golf ball to be examined, with a manual instrument manufactured by the Atti Engineering Company of Union City, N.J. This machine, equipped with a Federal Dial Gauge, Model D81-C, employs a calibrated spring under a known load. The sphere to be tested is forced a distance of 0.2 inch against this spring. If the spring, in turn, compresses 0.2 inch, the compression is rated at 100; it the spring compresses 0.1 inch, the compression value is rated as 0. Thus more compressible, softer materials will have a lower Atti gauge values than harder, less compressible materials. Compression measured with this instrument is also referred to as PGA compression.

As used herein, “COR” refers to Coefficient of Restitution, which is obtained by dividing a ball's rebound velocity by its initial (i.e. incoming) velocity. This test is performed by firing the samples out of an air cannon at a vertical steel plate over a range of test velocities (from 75 to 150 ft./sec). A golf ball having a high COR dissipates a smaller fraction of its total energy when colliding with the plate and rebounding therefrom than does a ball with a lower COR. Unless otherwise noted, the COR values reported herein are the values determined at an incoming velocity of 125 ft./sec.

The term “about,” as used herein in connection with one or more numbers or numerical ranges, should be understood to refer to all such numbers, including all numbers in a range.

As used herein, the term “pph” in connection with a batch formulation refers to parts by weight of the constituent per hundred parts of the base composition.

The present invention involves a method of creating in a multi-layered golf ball an intermediate or cover layer that is less dense than the layer beneath it. This is accomplished by the infrared heating of the intermediate or cover layer comprising an expandable polymeric composition containing a blowing agent that upon exposure to infrared heating expands to create the less dense layer.

An embodiment of the invention, employs a one piece core (up to a diameter of about 1.65 inches) and an intermediate and cover layer. Included in the intermediate layer is an expandable polymeric composition containing a blowing agent. On exposure to infrared radiation for a specific time and temperature, the expandable polymeric composition expands the layer from about 5 to 200% of the pre-expand thickness. The foamed intermediate layer is then less dense that the core beneath it. When a cover layer is foamed in this manner, it is less dense than the layer beneath it. As such, when the core has a Shore D hardness of greater than 50, preferably greater than 60, the intermediate layer is softer than the core by at least 3 Shore D points and preferably at least 5.

The core composition can be made from any suitable core materials including thermoset polymers, such as natural rubber, ethylene propylene rubber or epdiene monomer, polybutadiene (PBD), polyisoprene, styrene-butadiene or styrene-propylene-diene rubber, and thermoplastics such as ionomer resins, polyamides, polyesters, or a thermoplastic elastomer. Suitable thermoplastic elastomers include Pebax®, which is believed to comprise polyether amide copolymers, Hytrel®, which is believed to comprise polyether ester copolymers, thermoplastic urethane, and Kraton®, which is believed to comprise styrenic block copolymers elastomers. These products are commercially available from Elf-Atochem, E.I. Du Pont de Nemours and Company, various manufacturers, and Shell Chemical Company, respectively. The core materials can also be formed from a castable material. Suitable castable materials include those comprising a urethane, polyurea, epoxy, silicone, IPN's, etc.

The polybutadiene rubber composition preferably includes between about 2.2 parts and about 5 parts of a halogenated organosulfur compound. The halogenated conventional materials for such cores include core compositions having a base rubber, a cross-linking agent, filler and a co-cross-linking agent. The base rubber typically includes natural or synthetic rubbers. A preferred base rubber is 1,4-polybutadiene having a cis-structure of at least 40%. Natural rubber, polyisoprene rubber and/or styrene-butadiene rubber may be optionally added to the 1,4-polybutadiene. The initiator included in the core composition can be any known polymerization initiator that decomposes during the cure cycle. The cross-linking agent includes a metal salt of an unsaturated fatty acid such as a zinc salt or a magnesium salt of an unsaturated fatty acid having 3 to 8 carbon atoms such as acrylic or methacrylic acid. The filler typically includes materials such as tungsten, zinc oxide, barium sulfate, silica, calcium carbonate, zinc carbonate and the like. The polybutadiene rubber composition preferably includes between about 2.2 parts and about 5 parts of a halogenated organosulfur compound. The halogenated organosulfur compound may include pentafluorothiophenol; 2-fluorothiophenol; 3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol; 2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol; 2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol; 2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol; 4-chlorotetrafluorothiophenol; pentachlorothiophenol; 2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol; 2,3-chiorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol; 3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol; 2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol; pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol; 4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol; 3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol; 3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol; 2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol; 3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol; 2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol; 2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol; 2,3,5,6-tetraiodothiophenol; and their zinc salts, the metal salts thereof, and mixtures thereof, but is preferably pentachlorothiophenol or the metal salt thereof. The metal salt may be zinc, calcium, potassium, magnesium, sodium, and lithium, but is preferably zinc.

Additionally, suitable core materials may also include cast or reaction injection molded polyurethane or polyurea, including those versions referred to as nucleated, where a gas, typically nitrogen, is incorporated via intensive agitation or mixing into at least one component of the polyurethane. (Typically, the pre-polymer, prior to component injection into a closed mold where essentially full reaction takes place resulting in a cured polymer having reduced specific gravity.) These materials are referred to as reaction injection molded (RIM) materials. Alternatively, the core may have a liquid center.

The use of various formulation modifications in the polymeric composition may offer a plurality of means for accomplishing the end result, which is a less dense intermediate or cover layer.

In one embodiment, the invention involves the utilization of a chemical blowing agent that is a thermally decomposable inorganic blowing agent. Inorganic chemical agents may be preferred when the layer is a thermoplastic such as an ionomer, highly neutralized acid copolymer (HNP), polyolefin, etc. Some inorganic blowing agents may comprise ammonium carbonate and carbonates of alkali metals.

Organic blowing agents may include, but are not limited to organics such as azo and diazo compounds including any of the Celogens as manufactured by the Crompton Chemical Corporation, and nitroso compounds, sulfonylhydrazides, azides of organic acids and their analogs, triazines, tri- and tetrazole derivatives, sulfonyl semicarbazides, urea derivatives, quanidine derivatives, and esters such as alkoxyboroxines. Some chemical blowing agents liberate gases as a result of chemical interaction between components such as mixtures of acids and metals; mixtures of organic acids and inorganic carbonates, mixtures of nitrites and ammonium salts and the hydrolytic decomposition of urea.

Blowing agents can also be physical blowing agents that typically may comprise volatile liquids, such as freons, other halogenated hydrocarbons, water, aliphatic hydrocarbons, gases, and solid blowing agents. The solid blowing agents typically are adsorbents which include activated carbon, calcium carbonate, diatomaceous earth and silicates saturated with carbon dioxide. These adsorbents liberate gas as a result of desorption of gas. Another method of delivering the physical blowing agent is the use of hollow thermoplastic spheres that house a solvent, and upon the application of infrared radiation the solvent expands into a gas and thereby expanding the softened thermoplastic sphere. No matter the type of blowing agent used, the object is that the intermediate layer is less dense than the core layer and the cover layer is less dense than the intermediate layer.

The principles of curing with IR would work equally as well with one-piece, two-piece, multi-core, or multi-cover layered golf balls. Infrared radiation can be used to cross-link any portion of a golf ball, including the cover, coating and any intermediate layer as well as a core layer.

In one embodiment, a layer is cured by exposure to IR radiation wherein the post-curing (accelerated completion of cure) with infrared radiation is particularly suited to the post-curing of a polyurethane, polyurea, hybrid of the two, or the annealing of a crystalline/semi-crystalline thermoplastic polymer such as a partially or fully neutralized ionomer.

Intermediate and cover layers of golf balls may be cross-linked utilizing infrared radiation techniques, particularly to subassemblies of a thermoplastic layer comprising a peroxide over a diene core layer. For example, ionomer or non-ionic polyolefin comprising a high temperature half life peroxide may be molded (as a thermoplastic) over a conventional diene core followed by a post-molding infrared treatment that decomposes the peroxide generating free radicals which cross-link the host polymer via chain scission and subsequent initiation and/or via the reaction of previously unreacted diene groups of an ethylene-propylene-diene-monomer (EPDM) or polyisoprene, or styrene ethylene butylenes (SEBS), etc. For cross-linking, preferably about 0.01 to 5.0 parts of a peroxide may be added, more preferably 0.05 to 2.0 parts. Any additional ingredients such as nucleating agents, antioxidants, antizonants, processing aids such as metal salts of fatty acids, amino fatty acids, waxes, glycols, metal oxides such as zinc oxide, unsaturated coagents such as zinc diacrylate may also be added. In addition to foaming agents, the use of specific gravity lowering fillers/fibers/flakes/spheres/hollow microspheres/microballoons such as 3M glass, ceramic (zeeospheres), phenolic, as well as other polymer based such as Acrylonitrile, PVDC, etc. may also be used to supplement the infrared activated foaming/expansion agent.

Santoprene® 20340 is an example of a preferred intermediate layer comprises of dynamically vulcanized thermoplastic elastomer, functionalized styrene-butadiene elastomer, thermoplastic polyurethane or metallocene polymer or blends thereof. Suitable dynamically vulcanized thermoplastic elastomers include Santoprene®, Sarlink®, Vyram®, Dytron® and Vistaflex®. Santoprene® is the trademark for a dynamically vulcanized elastomer and is commercially available from Advanced Elastomer Systems. Examples of suitable functionalized styrene-butadiene elastomers include Kraton FG-1901x and FG-1921x, which is available from the Shell Corporation. Examples of suitable thermoplastic polyurethanes include Estane® 58133, Estane® 58134 and Estane® 58144, which are commercially available from the B. F. Goodrich Company. Suitable metallocene polymers whose melting points are higher than the cover materials can also be employed in the intermediate layer of the present invention. Further, the materials for the intermediate layer described above may be in the form of a foamed polymeric material. For example, suitable metallocene polymers include foams of thermoplastic elastomers based on metallocene single-site catalyst-based foams. Such metallocene-based foam resins are commercially available from Sentinel Products of Hyannis, Mass. Suitable thermoplastic polyetheresters include Hytrel® 3078, Hytrel® 3548, Hytrel® 4078, Hytrel® 4069, Hytrel® 6356, Hytrel® 7246, and Hytrel® 8238 which are commercially available from DuPont. Suitable thermoplastic polyetheramides include Pebax® 2533, Pebax® 3533, Pebax® 4033, Pebax® 5533, Pebax® 6333, and Pebax® 7033 which are available from Elf-Atochem. Suitable thermoplastic ionomer resins include any number of olefinic based ionomers including SURLYN® and lotek®, which are commercially available from DuPont and Exxon, respectively. The flexural moduli for these ionomers is about 1000 psi to about 200,000 psi. A suitable thermoplastic polyester is polybutylene terephthalate. Likewise, the dynamically vulcanized thermoplastic elastomers, functionalized styrene-butadiene elastomers, thermoplastic polyurethane or metallocene polymers identified above are also useful as the second thermoplastic in such blends. Further, the materials of the second thermoplastic described above may be in the form of a foamed polymeric material.

Such thermoplastic blends comprise about 1% to about 99% by weight of a first thermoplastic and about 99% to about 1% by weight of a second thermoplastic. Preferably the thermoplastic blend comprises about 5% to about 95% by weight of a first thermoplastic and about 5% to about 95% by weight of a second thermoplastic. In a preferred embodiment of the present invention, the first thermoplastic material of the blend is a thermoplastic polyetherester, such as Hytrel®.

The present invention also teaches the use of a variety of non-conventional cover materials. In particular, the covers of the present invention may comprise thermoplastic or engineering plastics such as ethylene or propylene based homopolymers and copolymers including functional monomers such as acrylic and methacrylic acid and fully or partially neutralized ionomers and their blends, methyl acrylate, methyl methacrylate homopolymers and copolymers, imidized, amino group containing polymers, polycarbonate, reinforced polyamides, polyphenylene oxide, high impact polystyrene, polyether ketone, polysulfone, poly(phenylene sulfide), reinforced engineering plastics, acrylonitrile-butadiene, acrylic-styrene-acrylonitrile, poly(ethylene terephthalate), poly(butylene terephthalate), poly(ethylene-vinyl alcohol), poly(tetrafluoroethylene) and their copolymers including functional comonomers and blends thereof. These polymers or copolymers can be further reinforced by blending with a wide range of fillers and glass fibers or spheres or wood pulp.

Additional preferred cover materials include thermoplastic or thermosetting polyurethane, such as those disclosed in U.S. Pat. Nos. 6,371,870; 6,210,294; 6,193,619; 5,908,358; 5,692,974; and 5,484,870; and metallocene or other single site catalyzed polymers such as those disclosed in U.S. Pat. Nos. 5,824,746; 5,703,166; 6,150,462; and 5,981,658.

While it is apparent that the illustrative embodiments of the invention herein disclosed fulfills the objectives stated above, it will be appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Therefore, it will be appreciated that the appended claims are intended to cover all such modifications and embodiments which come within the spirit and scope of the present invention. 

1. A multilayer golf ball comprising a core, an intermediate layer, and a cover, wherein the intermediate layer comprises an expandable polymeric composition containing a blowing agent therein, wherein the expandable polymeric composition expands from 5% to 200% of its pre-expand thickness when the expandable polymeric composition is heated with infrared radiation at a specific temperature and predetermined time.
 2. The golf ball of claim 1, wherein the blowing agent is a thermally decomposable inorganic chemical blowing agent selected from the group consisting of ammonium carbonate and carbonates of alkali metals.
 3. The golf ball of claim 1, wherein the blowing agent is a thermally decomposable organic blowing agent selected from the group consisting of azo and diazo compounds, nitroso compounds, sulfonylhydrazides, azides of organic acids and their analogs, triazines, tri-and tetrazole derivatives, sulfonyl semicarbazides, urea derivatives, guanidine derivatives, or esters such as alkoxyboroxines.
 4. The golf ball of claim 1, wherein the blowing agent is a de-volatizable physical blowing agent selected from a volatile liquid group consisting of freons, halogenated hydrocarbons, water, aliphatic hydrocarbons, gases, or solid adsorbents that liberate gas as a result of desorption of gas.
 5. The golf ball of claim 4, wherein the solid adsorbents are selected from a group consisting of activated carbon, calcium carbonate, diatomaceous earth, and silicates saturated with carbon dioxide.
 6. The golf ball of claim 1, wherein the expandable polymeric composition comprises a plurality of thermally expandable polyspheres encapsulating an expandable blowing agent in the form of a solvent, wherein when heated by infrared radiation the solvent expands into a gas that is released into the layer.
 7. The golf ball of claim 1, wherein the intermediate layer has a density that is lower than the density of the core.
 8. The golf ball of claim 11, wherein the intermediate layer includes a blowing agent that liberates a gas as a result of a chemical interaction between components selected from a group consisting of mixtures of acids and metals, mixtures of organic acids and inorganic carbonates, mixtures of nitrites and ammonium salts and the hydrolytic decomposition of urea.
 9. The golf ball of claim 1, wherein the intermediate layer is a water vapor barrier layer.
 10. A method of forming a foamed intermediate layer in a multi-layer golf ball, the method comprising: providing a core; encapsulating the core with a intermediate layer comprising an expandable polymeric composition containing a blowing agent; heating the intermediate layer with infrared radiation at a specific temperature for a pre-determined time, wherein the expandable polymeric composition expands from 5% to 200% to create a foamed layer; and enclosing the intermediate layer with a cover.
 11. The method of claim 10, wherein the blowing agent is a thermally decomposable inorganic chemical blowing agent selected from the group consisting of ammonium carbonate and carbonates of alkali metals.
 12. The method of claim 10, wherein the blowing agent is a thermally decomposable organic blowing agent selected from the group consisting of azo and diazo compounds, nitroso compounds, sulfonylhydrazides, azides of organic acids and their analogs, triazines, tri-and tetrazole derivatives, sulfonyl semicarbazides, urea derivatives, guanidine derivatives, or esters such as alkoxyboroxines.
 13. The method of claim 10, wherein the blowing agent is a devolatizable physical blowing agent selected from a volatile liquid group consisting of freons, halogenated hydrocarbons, water, aliphatic hydrocarbons, gases, or solid adsorbents that liberate gas as a result of desorption of gas.
 14. The method of claim 13, wherein the solid adsorbents are selected from a group consisting of activated carbon, calcium carbonate, diatomaceous earth, and silicates saturated with carbon dioxide.
 15. The method of claim 10, wherein the expandable polymeric composition comprises a plurality of thermally expandable polyspheres encapsulating an expandable blowing agent in the form of a solvent which expands into a gas that is released into the layer.
 16. The method of claim 10, wherein the intermediate layer has a density that is lower than the density of the core.
 17. The method of claim 10, wherein the cover layer has a density lower than the density of the intermediate layer.
 18. The method of claim 10, wherein the intermediate layer includes a blowing agent that liberates a gas as a result of a chemical interaction between components selected from a group consisting of mixtures of acids and metals, mixtures of organic acids and inorganic carbonates, mixtures of nitrites and ammonium salts and the hydrolytic decomposition of urea. 